The present disclosure relates to a display employing a thin film transistor (TFT) in which an active layer is made of an oxide semiconductor and a method of manufacturing the display.
TFTs are widely applied, as a basic technology, to liquid crystal displays, organic EL displays, and the like. Generally, a semiconductor layer serving as an active layer of a TFT is made of amorphous silicon (a-Si:H) or poly silicon, but in recent years, oxide semiconductors such as metal oxides which may be formed by inexpensive apparatuses adopting a sputtering method or the like are also used to form such a semiconductor layer. However, if light (especially ultraviolet light of 420 nm or less) is irradiated on a semiconductor layer made of an oxide semiconductor, its TFT characteristics may be varied by photoinduction, or more specifically, its threshold level voltage (Vth) may be shifted to negative (−) direction.
In order to solve this issue, for example, Japanese Unexamined Patent Application Publication No. 2007-115902 discloses a TFT employing a light shielding film provided on the rear face of a substrate. In addition, for example, Japanese Unexamined Patent Application Publication No. 2009-224354 discloses a bottom-gate type TFT employing a light-absorbing layer provided between a gate electrode and an active layer, and Japanese Unexamined Patent Application Publication No. 2007-150157 discloses a TFT employing a base material (substrate) made of a material in which transmittance of light having a wavelength shorter than the band gap energy is 10% or less.